Nano ID

alt="Nano ID logo by Anton Lovchikov" width="180" height="94">

A tiny, secure, URL-friendly, unique string ID generator for JavaScript.

* Small. 141 bytes (minified and gzipped). No dependencies.
[Size Limit] controls the size.
* Safe. It uses cryptographically strong random APIs
and tests distribution of symbols.
* Fast. It’s 16% faster than UUID.
* Compact. It uses a larger alphabet than UUID (A-Za-z0-9_-).
So ID size was reduced from 36 to 21 symbols.

``js
var nanoid = require('nanoid')
model.id = nanoid() //=> "V1StGXR8_Z5jdHi6B-myT"
`

The generator supports Node.js, React Native, and [all browsers].

[all browsers]: http://caniuse.com/#feat=getrandomvalues
[Size Limit]: https://github.com/ai/size-limit


alt="Sponsored by Evil Martians" width="236" height="54">





Security

*See a good article about random generators theory:
[Secure random values (in Node.js)]*




$3

Instead of using the unsafe Math.random(), Nano ID uses the crypto module
in Node.js and the Web Crypto API in browsers. These modules use unpredictable
hardware random generator.




$3

random % alphabet is a popular mistake to make when coding an ID generator.
The spread will not be even; there will be a lower chance for some symbols
to appear compared to others—so it will reduce the number of tries
when brute-forcing.

Nano ID uses a [better algorithm] and is tested for uniformity.

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[Secure random values (in Node.js)]: https://gist.github.com/joepie91/7105003c3b26e65efcea63f3db82dfba
[better algorithm]: https://github.com/ai/nanoid/blob/master/format.js




Comparison with UUID

Nano ID is quite comparable to UUID v4 (random-based).
It has a similar number of random bits in the ID
(126 in Nano ID and 122 in UUID), so it has a similar collision probability:

> For there to be a one in a billion chance of duplication,
> 103 trillion version 4 IDs must be generated.

There are two main differences between Nano ID and UUID v4:

1. Nano ID uses a bigger alphabet, so a similar number of random bits
are packed in just 21 symbols instead of 36.
2. Nano ID code is 3 times less than uuid/v4 package:
141 bytes instead of 435.




Benchmark

`rust
$ ./test/benchmark
nanoid 693,132 ops/sec
nanoid/generate 624,291 ops/sec
uid.sync 487,706 ops/sec
uuid/v4 471,299 ops/sec
secure-random-string 448,386 ops/sec
shortid 66,809 ops/sec

Async:
nanoid/async 105,024 ops/sec
nanoid/async/generate 106,682 ops/sec
secure-random-string 94,217 ops/sec
uid 92,026 ops/sec

Non-secure:
nanoid/non-secure 2,555,814 ops/sec
rndm 2,413,565 ops/sec
`




Usage

$3

The main module uses URL-friendly symbols (A-Za-z0-9_-) and returns an ID
with 21 characters (to have a collision probability similar to UUID v4).

`js
const nanoid = require('nanoid')
model.id = nanoid() //=> "Uakgb_J5m9g-0JDMbcJqLJ"
`

Symbols -,.() are not encoded in the URL. If used at the end of a link
they could be identified as a punctuation symbol.

If you want to reduce ID length (and increase collisions probability),
you can pass the length as an argument.

`js
nanoid(10) //=> "IRFa-VaY2b"
`

Don’t forget to check the safety of your ID length
in our [ID collision probability] calculator.

[ID collision probability]: https://zelark.github.io/nano-id-cc/

$3


Do not use a nanoid for key prop. In React key should be consistence
between renders. This is bad code:

`jsx
/ DON’T DO IT /
`

This is good code. Note, that we added "input" string in front of id,
because Nano ID could be started from number. HTML ID can’t be started
from the number.

`jsx
id = 'input' + nanoid()

render () {
return <>
Label text

;
}
}
`

$3

To generate secure random IDs in React Native, you must use
[a native random generator] and asynchronous API:

`js
const generateSecureRandom = require('react-native-securerandom').generateSecureRandom
const format = require('nanoid/async/format')
const url = require('nanoid/url')

async function createUser () {
user.id = await format(generateSecureRandom, url, 21);
}
`

[a native random generator]: https://github.com/rh389/react-native-securerandom




$3

`js
const mySchema = new Schema({
_id: {
type: String,
default: () => nanoid(10)
}
})
`




$3

Web Workers don’t have access to a secure random generator.

Security is important in IDs, when IDs should be unpredictable. For instance,
in “access by URL” link generation.

If you don’t need unpredictable IDs, but you need Web Workers support,
you can use non‑secure ID generator.

`js
const nanoid = require('nanoid/non-secure')
model.id = nanoid() //=> "Uakgb_J5m9g-0JDMbcJqLJ"
`




Async

To generate hardware random bytes, CPU will collect electromagnetic noise.
During the collection, CPU doesn’t work.

If we will use asynchronous API for random generator,
another code could be executed during the entropy collection.

`js
const nanoid = require('nanoid/async')

async function createUser () {
user.id = await nanoid()
}
`

Unfortunately, you will not have any benefits in a browser, since Web Crypto API
doesn’t have asynchronous API.




Custom Alphabet or Length

If you want to change the ID's alphabet or length
you can use the low-level generate module.

`js
const generate = require('nanoid/generate')
model.id = generate('1234567890abcdef', 10) //=> "4f90d13a42"
`

Check the safety of your custom alphabet and ID length
in our [ID collision probability] calculator.
You can find popular alphabets in [nanoid-dictionary].

Alphabet must contain 256 symbols or less.
Otherwise, the generator will not be secure.

Asynchronous and non-secure API is also available:

`js
const generate = require('nanoid/async/generate')
async function createUser () {
user.id = await generate('1234567890abcdef', 10)
}
`

`js
const generate = require('nanoid/non-secure/generate')

user.id = generate('1234567890abcdef', 10)
`

[ID collision probability]: https://alex7kom.github.io/nano-nanoid-cc/
[nanoid-dictionary]: https://github.com/CyberAP/nanoid-dictionary




Custom Random Bytes Generator

You can replace the default safe random generator using the format module.
For instance, to use a seed-based generator.

`js
const format = require('nanoid/format')

function random (size) {
const result = []
for (let i = 0; i < size; i++) {
result.push(randomByte())
}
return result
}

format(random, "abcdef", 10) //=> "fbaefaadeb"
`

random callback must accept the array size and return an array
with random numbers.

If you want to use the same URL-friendly symbols with format,
you can get the default alphabet from the url file.

`js
const url = require('nanoid/url')
format(random, url, 10) //=> "93ce_Ltuub"
`

Asynchronous API is also available:

`js
const format = require('nanoid/async/format')
const url = require('nanoid/url')

function random (size) {
return new Promise(…)
}

async function createUser () {
user.id = await format(random, url, 10)
}
`

Tools

* [ID size calculator] to choice smaller ID size depends on your case.
* [nanoid-dictionary] with popular alphabets to use with nanoid/generate.
* [nanoid-cli] to generate ID from CLI.
* [nanoid-good] to be sure that your ID doesn't contain any obscene words.

[nanoid-dictionary]: https://github.com/CyberAP/nanoid-dictionary
[ID size calculator]: https://zelark.github.io/nano-id-cc/
[nanoid-cli]: https://github.com/twhitbeck/nanoid-cli
[nanoid-good`]: https://github.com/y-gagar1n/nanoid-good

Other Programming Languages

* C#
* Clojure and ClojureScript
* Crystal
* Dart
* Go
* Elixir
* Haskell
* Java
* Nim
* PHP
* Python with dictionaries
* Ruby
* Rust
* Swift

Also, [CLI tool] is available to generate IDs from a command line.

[CLI tool]: https://github.com/twhitbeck/nanoid-cli